Comparative study of neurosecretory cells of the hypothalamus and interactions between cells of specific nuclei is being carried out. We will study orthodromic and antidromic propagation of impulses and compare our observation in similar studies made of motoneurons within the cord. Both in situ and isolated preparation of hypothalamo-hypophysial system are carried out. Our ultimate interest is in the control of neurosecretory cell activity and integrative action of the hypothalamus as expressed through neuronal and humoral pathways.